Good fashion designer's stimulating (7)
I believe the answer is:
piquant
'stimulating' is the definition.
(similar in meaning)
'good fashion designer's' is the wordplay.
'good' becomes 'pi' (I've seen this in other clues).
'fashion designer' becomes 'quant' (I've seen this before).
'pi'+'quant'='PIQUANT'
(Other definitions for piquant that I've seen before include "Having a pungent taste" , "Appetising, tangy" , "Spicy" , "Pleasantly pungent, stimulating" , "Flavoursome" .)